The present invention relates to a transportable concrete mixing plant, in which all the components can preferably be transported in standard shipping containers.
Transportable concrete mixing plant is used by civil construction companies on building sites whose concrete requirement cannot be covered practically by the inward transport of concrete mixed at another site (for example in stationary transportable concrete mixing plant), for example using the known concrete mixing vehicles. This case may arise on large building sites, for example within the context of traffic projects, in which the concrete requirement is extremely high. However, the inward transport of concrete by means of concrete mixing vehicles may not be practical either in the case of very isolated building sites, so that in this case, too, a concrete mixing plant is needed on site.
For this reason, numerous civil construction companies have transportable concrete mixing plant, which is erected on a building site to produce concrete on site. For this purpose, concrete mixing plant of this type is formed from a number of mixing plant components which can be connected detachably to one another, which are transported to the building site individually, for example using heavy goods vehicles, and are assembled there.
In this case, the problem often arises that the mixing plant components, such as concrete mixers, cement silos, conveyor belts and the like, have dimensions which are unusual, because of their function, for which reason their transport, for example on heavy goods vehicles, is made more difficult. It is often necessary to apply for special approvals, which entails additional costs and delivery-date problems. In the case of transport by marine freighter or goods train, such as is necessary in the case of construction companies which are active superregionally or even worldwide, these unusual dimensions, excessive widths and the like of the mixing plant components lead to considerable costs and delays during transport.
It is therefore the object of the invention to provide a transportable concrete mixing plant whose components can be transported more quickly and more cost-effectively without using means for this, such as packaging devices or covering materials, which are not required for the actual operation of the concrete mixing plant, and therefore would give rise to unnecessary costs and an increased requirement for space on the building site.
According to the invention, this object is achieved by a transportable concrete mixing plant comprising a number of mixing plant components which can be connected detachably to one another and which during transport are accommodated in a number of containers, at least some of these containers, preferably all of these containers, serving as a load-bearing structure for mixing plant components and/or containers for concrete raw materials when the mixing plant is operating.
The invention offers the advantage that the containers containing the mixing plant components can be offloaded quickly, worldwide, at offloading stations of harbours, railway stations and the like, using the cranes and the like which are available there for this purpose. In addition, the transport of containers, using marine freighters, goods trains, heavy goods vehicles and the like, does not present any difficulties, so that the relatively rapid and cost-effective transport of the mixing plant components is possible, even over great distances.
The invention also offers the advantage that the containers protect the mixing plant components during transport and, in addition, offer transport volumes for the equipment needed additionally during the use of the concrete mixing plant.
Furthermore, the use of containers as a load-bearing structure for mixing plant components or as containers for concrete raw materials, such as aggregates, binders, water, additional compounds and additives, when the mixing plant is operating, offers the advantage that no separate devices have to be carried at the same time for this purpose. In this case, the containers can be used both as an open load-bearing structure similar to a framework and as a closed load-bearing structure similar to a housing. This means a reduction in the outlay on transport and, in addition, always ensures the completeness of all the components needed for the operation of the concrete mixing plant.
In order to be able to configure the transport of the concrete mixing plant particularly simply, it is proposed that the containers be standard shipping containers or be capable of being combined into standard shipping containers which can be transported in a standard way in accordance with international regulations, especially by ship, rail and heavy goods vehicle. The transport of the concrete mixing plant can then be carried out with any marine container freighter, container goods train and so on, which permits particularly rapid and cost-effective transport.
In order to be able to utilize the load-bearing structure or container function of the containers in a simple way, provision is made for at least some containers to have openable hatches through which, when the mixing plant is operating, mixing plant components accommodated in various containers, at least to some extent, can work together. Following transport, the containers are set up first of all on the building site at predefined relative positions beside one another or above one another, then the hatches in the walls of the containers are opened and the mixing plant components contained in the respective containers are, if appropriate, drawn out through the opened hatches in such a way that they can work together when the plant is operating. This offers the advantage that it is generally not necessary to lift mixing plant components out of their respective container.
In order to implement a transportable concrete mixing plant according to the invention, it is proposed that it have at least one mixer container, which contains at least one concrete mixer for the mixing of aggregates, of preferably cement-containing binder, of water and of additional compounds and additives for producing concrete and, by means of the fitting of appropriate components, can be extended in such a way that the performance is increased to correspond to the requirements of the building site, for example expansion from one to up to four mixers with corresponding enlargement of the number of silos, metering systems, conveying devices and so on. In this case, the concrete mixers used can be, for example, double-shaft mixers, known per se, in order to achieve high concrete production speeds in civil engineering, these mixers being filled from above with aggregates and binder and having at the bottom a bottom emptying opening, which can be closed as desired, for the removal of concrete. The number of mixers per container is essentially restricted by their space requirement and the permissible total weight of the container.
In this case, provision is advantageously made for that wall of the mixer container which is located above each mixer when the plant is operating to have a hatch which can be opened above each mixer. Through this hatch, which is opened when the plant is operating, the aggregates and the binder and, if necessary, additives are fed to the concrete mixer.
In an advantageous further development of a transportable concrete mixing plant of this type, it is proposed that it comprise at least one stackable mixer container which, when the mixing plant is operating, is arranged on the mixer container and which contains loading means for the introduction of binder, preferably cement, and of aggregates and, if necessary, additives into each mixer through the openable hatches located in the upper wall of the mixer container and through hatches which can be opened and are located in the bottom wall of the stackable mixer container, opposite the hatches. In the simplest case, these loading means could comprise a pipe which opens from above into the concrete mixer through the opened hatches.
However, provision is advantageously made for the loading means for each mixer to comprise a pilot silo for aggregates and a compartment for binders and, if apropriate, for additives, which in each case can be of approximately funnel-like design.
For the precise metering of the binder and, if appropriate, of the additives, it is expedient for the compartment to contain a balance. When a previously determined desired quantity is reached, the compartment outputs its contents to the concrete mixer.
In an advantageous development of the invention, provision is made for a conveying means leading through an opened hatch in a wall of the stackable mixer container into the latter for the introduction of binder and, if appropriate, additive into the stackable mixer container. In this case, this conveying means is arranged in such a way that its end that is downstream in the conveying direction is located over the hopper, so that binder and/or the additive falls into the hopper at this end.
Since at least some parts of the conveying means generally run in the open air, the binder or the additive conveyed by it must be protected against rain, wind and so on. For this reason, provision is advantageously made for the conveying means leading into the stackable mixer container to be a feed screw. In a feed screw of this type, a screw drive rotates in a pipe, which protects the material from the abovementioned influences. If this protection is ensured by other measures, then it is possible for the conveying means, if appropriate, to be designed as a conveyor belt as well.
In a development of the invention, effective feeding of aggregates can be ensured by the fact that, when at least two mixers are used, an aggregate conveying means is provided having a running direction which can be changed over optionally in order co feed the aggregates to the loading means respectively assigned to a mixer. The aggregate conveying means is in this case arranged in such a way that each of its two ends is located over a loading means. If the aggregates are fed to the aggregate conveying means between its two ends, in each case one loading means can be supplied with aggregates by optionally changing over the running direction of the aggregate conveying means.
In an efficient development of such a concrete mixing plant according to the invention, provision is made that, when at least three mixers are used, the aggregate conveying means can be moved to and fro over the loading means for the aggregates, between a number of operating positions in which each end of the aggregate conveying means is assigned to a loading means for aggregates. Thus, for example, four mixers arranged essentially equidistantly in a row, or the loading means assigned to them, can be supplied with aggregates by the aggregate conveying means being moved to and fro between two operating positions, and both running directions of the conveying means being utilized in each operating position.
Since the aggregate conveying means runs protected, essentially inside the stackable mixer container, for reasons of simplicity provision is made for the aggregate conveying means to be a conveyor belt.
It is expedient if, in the transportable concrete mixing plant according to the invention, an inclined conveying means passing through at least one wall of the stackable mixer container, through an opened hatch, is provided for introducing the aggregates into the stackable mixer container. This inclined conveying means receives the aggregates essentially at the level of the standing surface of the transportable concrete mixing plant according to the invention, and conveys them, on the aggregate conveying means described above, into the stackable mixer container standing on the mixer container.
Since this aggregate conveying process requires a length of the inclined conveying means which, under certain circumstances, exceeds the length of a standard shipping container, in an advantageous development of the invention provision is made for the inclined conveying means to be a conveyor belt which, during transport, is accommodated in the folded-up state in an inclined conveyor-belt container. Folding up the inclined conveyor belt in this way may be achieved by means of a number of hinges in an inclined conveyor-belt frame bearing the inclined conveyor belt.
As explained above, mixers with bottom emptying are expediently used. In this case, provision is made for that wall of the mixer container which is at the bottom when the plant is operating to have, under each mixer, a hatch which can be opened to remove concrete from the mixer container. It is thus possible for concrete to be removed from the mixer through the opened hatch in the lower wall of the mixer container.
This configuration is particularly advantageous when the mixer container is erected on a standing surface of a mixer frame which is dimensioned such that concrete can be discharged through the openable hatches, in order to remove concrete from the mixer container, into a heavy goods vehicle or the like provided underneath the standing surface. If more than one mixer is used, for example in the case of the embodiment shown later of the concrete mixing plant according to the invention having four mixers, it is also possible for two heavy goods vehicles to be provided xe2x80x9cback to backxe2x80x9d under the standing surface of the mixer frame and to be loaded with concrete simultaneously or directly one after another.
Instead of using a mixer frame of this type, however, it is also possible when the plant is operating, for the mixer container to stand on an offloading container, in whose top wall hatches which can be opened are provided, opposite the openable hatches in the bottom wall of the mixer container. In this case, the concrete discharged from the mixer falls into the offloading container and must be transported onwards from there.
This onward transport can be ensured by there being provided in one end wall of the offloading container an openable hatch, through which there passes a concrete conveying device, which during transport is accommodated completely in the offloading container, for conveying the concrete, for example to a heavy goods vehicle or the like provided beside the offloading container. This concrete conveying device could be a conveyor belt which is folded up during transport, in a way similar to the inclined conveying means presented above, and which is extended for operation.
However, a simpler and more cost-effective configuration consists in the concrete conveying device comprising an upper concrete collecting belt which, when the plant is operating, is accommodated completely in the offloading container and a lower concrete conveyor belt which, when the plant is operating, passes through the openable hatch in the end wall of the offloading container. The concrete discharged from the mixer container therefore falls firstly onto the upper concrete collecting belt and, at the end of the latter, onto the lower concrete conveyor belt running below it, which conveys it out of the offloading container.
In a development of the concrete mixing plant according to the invention, provision is made for it to comprise at least one binder silo container as a storage means for bander or the like, as well as, if appropriate, a corresponding silo container for concrete additive. Just its use of a container as a binder silo means a great simplification in the transport of a transportable concrete mixing plan, since conventional binder silos, because of their size and of their form, which is generally characterized by a round cross section, present difficulties during offloading and transport.
Provision is expediently made in this case for each binder silo or additive silo container, respectively, to stand upright on its end face. This construction reduces the space requirement on the building site and facilitates the removal of binder from the binder silo container.
In the case of building sites with a large concrete demand, provision is made for at least two binder silo or additive silo containers to be erected beside one another or on one another. The possibility, which is generally not provided in the case of conventional binder silos but can be implemented without difficulty when binder silo containers are used, of stacking such storage means for binders on one another, oriented vertically, permits the provision of a large supply of binder with a low requirement for space on the building site. If two binder silo containers are erected on one another, a continuous binder silo can be formed by opening hatches in the end walls resting on each other.
In order to solve the problem, known from conventional binder silos, of a largely emptied silo tipping over, for example in the event of severe wind, in the concrete mixing plant according to the invention, provision is made for each binder silo or additive silo container erected upright to be fastened, by means of transverse struts, to the stackable mixer container and/or to the mixer container and/or to the offloading container or to the mixer frame for the purpose of stabilization. This type of fastening effects significantly greater stabilization of each binder silo container than the fastening to the ground which is generally used in conventional binder silos.
In order to provide a flat substrate for the upright silo containers, and for their further stabilization, provision is made for each silo container which is not standing on a further silo container, and the offloading container and/or the mixer frame to be fastened on a common baseplate. In the simplest case, this baseplate may comprise an arrangement of girders, for example I-girders made of steel.
In order to remove the binder or additive from the silo containers, provision is preferably made for each silo container which is not standing on a further silo container, when in its operating state, to contain in its lower region a hopper whose upper cross section essentially corresponds to the cross section of the silo container and which tapers downwards.
The walls of this hopper can also be formed by metal plates which run obliquely away from the side walls of the silo container and, when operating, run towards each other at the bottom, and in this arrangement are fastened rigidly in the silo container, or they can rest on walls of the silo container during transport and, when operating, can be folded out into the above-described working position.
For reasons of safety, provision may also be made for each silo container which is not standing on a further silo container to have, on its end face which is located at the bottom when it is operating, a concrete slab for stabilization. A concrete slab of this type is expediently fastened rigidly to the corresponding end face.
In order to remove the binder or additive, provision is preferably further made, in the operating state, for a binder or additive conveying means to be arranged underneath the hopper opening, and to pass through a side wall of the container through an opened hatch. During transport, this binder conveying means is expediently kept in the silo container and, on the building site, is drawn out through the opened hatch.
Provision is preferably also made here for the binder or additive conveying means to be a feed screw. In this way, the binder is also protected against the influence of weather in this region of the concrete mixing plant according to the invention.
For the further transport of the binder or additive, provision is made for the binder or additive conveying means to work together with a vertical conveying means which runs essentially vertically or obliquely upwards on an outer wall of the silo container in such a way that it can transfer binder or additive to the latter for onward conveyance, the vertically or obliquely running conveying means advantageously also being a feed screw.
In this case, provision is made for the vertically or obliquely running conveying means to work together with the binder or additive conveying means which runs partly in the stackable mixer container in such a way that it transfers binder or additive to the latter for onward conveyance. Such a transfer of binder from a feed screw to another feed screw can be ensured by the pipes surrounding the two feed screws having openings located close beside one another, between which there runs a slide designed as a pipe or a chute.
For the purpose of transporting the binder or the additive from the silo to the mixer, instead of the three individual conveying means, only one conveying means, advantageously a feed screw, can be used.
In order to make work easier on the concrete mixing plant according to the invention, provision can further be made for ladders, safety railings and the like on the outside of the binder silo container, which during transport are accommodated in a container, preferably this container.
In order to complete the equipment of the concrete mixing plant according to the invention, provision is made for a concrete finisher and/or a working platform or the like, during transport, to be accommodated in a container, preferably a silo container. In particular in the case of large concrete mixing plant according to the invention, in which empty binder silo containers are carried as well during transport, such devices can be transported at the same time without difficulty. This also reduces the transport costs for these machines, in particular in the case of marine transport, since these machines otherwise cannot be transported on container ships.
In a development of the transportable concrete mixing plant according to the invention, provision is made for it to comprise at least one metering-unit container which contains a metering device for metering the aggregates. The metering of the aggregates is carried out in this case in the metering-unit container and coordinated with the above-described metering of the binder or additive into the binder hopper. Monitoring and possible correction of the quantity of aggregates metered in this way can be carried out via an additional balance in the pilot silo for aggregates in the stackable mixer container.
Simple configuration of a metering device of this type is possible if the metering device for aggregates has at least one weighing conveyor belt for weighing and transporting the aggregates, and at least one loading means assigned to the weighing conveyor belt. Weighing conveyor belts of this type for the simultaneous weighing and transport of a material are known per se and will not be described further here.
In order to permit the reliable and rapid feeding of aggregates through the loading means to the weighing conveyor belt, the invention provides for each loading means to be formed by a hopper which is arranged above the weighing conveyor belt, which tapers downwards and, upwards, opens wide towards an openable hatch in chat side wall of the metering-unit container which is at the too when operating. In this way, aggregates can be introduced into the top opening of the hopper, for example by means of a wheeled loader, without attention having to be paid to particular precision during this filling operation.
It is possible to put only aggregates with a specific grain size into each hopper. These different aggregates can then be let out one after another onto the weighing conveyor belt, which weighs the aggregates of each grain size and ensures that they are metered in a predetermined ratio. However, it is also possible to perform the desired mixing of the aggregates with various grain sizes outside the metering-unit container and to put this mixture into each hopper of the metering-unit container.
A further simplification of this filling operation, as well as the possibility of simultaneous filling using a number of wheeled loaders, is provided if each metering-unit container is assigned a stackable metering container of essentially the same length, whose halves, when operating, are placed beside each other and parallel to the metering-unit container, oriented with the latter, and which, with the aid of a baffle-plate device and openable hatches in the upper side wall of the metering-unit container and in the lower wall of each half of the stackable metering container, enlarge the effective upper filling cross section of each hopper in the metering-unit container.
In this embodiment, provision is preferably made for the baffle-plate device to comprise baffle plates which are permanently arranged in the stackable metering container and run obliquely and which, in the operating state, lengthen the walls of each hopper in the metering-unit container upwards into the halves of the stackable metering container. By means of this measure, the upper filling cross section of each hopper in the metering-unit container can be approximately doubled by comparison with a design without a stackable metering container.
A further enlargement of the upper filling cross section of each hopper may be achieved if the baffle-plate device further comprises baffle plates which are rotatably mounted essentially at corners of the halves of the stackable metering container and, in the operating state, are folded out of the stackable metering container in such a way that they enlarge the hopper opening at the top. Overall, this permits an upper filling cross section to be achieved which allows the simultaneous filling of the metering device for aggregates using a number of wheeled loaders.
In order to convey onwards the aggregates metered and transported with the aid of the weighing conveying belt, the invention provides that, in the metering-unit container, an output conveying means is provided which runs underneath the weighing conveying belt, parallel to the latter, and can be displaced in the longitudinal direction, partly out of the metering-unit container, through an openable hatch in an end face of the metering-unit container. During transport, this output conveying means is accommodated completely in the metering-unit container and, for the purpose of operation, is drawn out through the opened hatch in the end face of the metering-unit container.
For the reasons already mentioned above for aggregates, the output conveying means can be a conveyor belt here as well.
For the onward transport of the aggregates, provision is preferably made, according to the invention, for the end of the output conveying means which, in the operating state, is located outside the metering-unit container to be arranged above the inclined conveying means for feeding aggregates to the stackable mixer container. The aggregates therefore fall onto the above-described inclined conveying means at that end of the output conveying means which is located outside the metering-unit container. In this case, in order to avoid as far as possible aggregates xe2x80x9cfalling by the waysidexe2x80x9d, a hopper can be arranged at the lower end of the inclined conveying means.
In a development of the invention, the transportable concrete mixing plant can also comprise an additive container to accommodate concrete additives. The selection of such additives depends on the intended use of the concrete to be produced, as known in civil engineering.
In a development of the transportable concrete mixing plant according to the invention, provision is made for it also to contain a control-station container, in which a control station for controlling the components of the concrete mixing plant is accommodated. Control stations of this type for the essentially computer-aided monitoring and control of concrete mixing plant are known in civil engineering and will not be explained further here.
In addition, the concrete mixing plant according to the invention can also comprise a water container to hold the water needed for the production of concrete, or a container which accommodates water and/or concrete additives.
As a result of covering, insulation, partitioning, warming or heating (with warm air, heating steam, heating coils and so on) of the individual mixing plant components (in particular the mixer container together with the stackable mixer container, conveyor belts, metering-unit container, additive container and water container together with delivery lines), the transportable concrete mixing plant according to the invention makes mixing operation possible even at ambient temperatures below zero degrees Celsius.
In a development of the transportable concrete mixing plant according to the invention, provision can be made for it to have a pressure conveying device, preferably a compressed-air conveying device, for conveying by pressure from at least one silo container. A pressure conveying device of this type is particularly advantageous when other conveying devices, such as feed screws, are subjected to high wear and/or a high risk of blockage because of the respective operating conditions, for example because of the binder or additive selected. The principle of pressure conveyance of such materials is known per se and can also be used for putting binders or additives into a silo container.
In an advantageous refinement of a pressure conveying device of this type, provision is made for it to comprise a collecting vessel with a compressor and a delivery hose connected to the collecting vessel. Of course, these components of the pressure conveying device can also be accommodated in a container during transport.
In principle, in the case of this construction it is possible to convey binders and additives through the delivery hose directly to a binder hopper in a stackable mixer container. However, since the pressure conveyance of materials of this type into a binder hopper could falsify the weighing of the material carried out therein, provision is advantageously made for the concrete mixing plant according to the invention to have at least one intermediate binder container for the intermediate storage of binder, which is preferably erected on at least one stackable mixer container, the delivery hose expediently opening into the at least one intermediate binder container. In this case, an intermediate binder container of this type erected on a stackable mixer container likewise has hatches through which the delivery hose opens into the said container when the transportable concrete mixing plant according to the invention is operating, or through which the material conveyed in can be fed to a binder hopper associated with a mixer.
This feeding is preferably carried out in such a way that the at least one intermediate binder container contains a hopper, which opens into a rotary feeder which is arranged above a binder compartment in a stackable mixer container. A rotary feeder of this type functions in a similar way to a rotating door provided in buildings and permits the feeding of binder or additive into the binder compartment without pressure being applied by the pressure conveying device. Rotary feeders of this type are known per se in this branch of engineering and will therefore not be explained specifically.
In a particularly space-saving embodiment of the invention, provision is made for the collecting vessel and the compressor to be arranged in the lower region of the silo container. In this case, the collecting vessel can be installed permanently in the respective silo container, while the compressor and the delivery hose are transported in the same container or in a different container when the concrete mixing plant is being transported. However, it is also possible to arrange the collecting vessel outside the silo container, in order to use this container as effectively as possible for the intermediate storage of binder or additive.
In a development, the transportable concrete mixing plant according to the invention can have binder silo containers and/or additive silo containers which, when operating, are stacked on one another and parallel to one another with essentially horizontal orientation. A xe2x80x9chorizontalxe2x80x9d orientation of silo containers in this way, with the container longitudinal axis running essentially horizontally, certainly requires an increased amount of space by contrast with the abovementioned vertical orientation of silo containers but permits the silo containers to be erected more stably and better protected against any possible tilting. Such a horizontal arrangement of silo containers can therefore be provided, for example, on building sites on which increased stability requirements have to be placed on the silos because of severe winds.
In order to form a continuous binder or additive silo from silo containers of this type stacked on one another and parallel co one another with essentially horizontal orientation, these silo containers can in turn be equipped with openable hatches. Since, when a silo container with a relatively large base area is stacked parallel one on another on a top surface which is aligned in parallel and is of essentially the same size and belongs to a silo container arranged underneath, and the size of conventional openable hatches in container surfaces is generally restricted, in order to ensure a good flow of binder or additive from upper to lower silo containers, provision is advantageously made for the binder silo containers and/or additive silo containers stacked on one another and parallel to one another with essentially horizontal orientation to each have removable bottom and top surfaces. In the case of such silo containers, therefore, when the concrete mixing plant according to the invention is operating, not only are hatches opened in the bottom and top surfaces of the containers, but rather these bottom and top surfaces are removed completely. This avoids the occurrence of corners and niches within a silo, in which binders or additives could accumulate.
Since even a silo constructed in this way must be closed at the top and bottom when operating, provision is expediently made for the transportable concrete mixing plant to have a final silo container which can essentially be divided into two halves and whose halves, when operating, form the lowest and, respectively, the uppermost container of a group of silo containers stacked on one another and parallel to one another. In this case, the dividable final silo container can accommodate those components which the lowest and uppermost container are intended to contain when the plant is operating. Thus, the uppermost container of the silo may have a filter which filters binders and/or additives out of the air expelled when filling the silo. The lowest container can contain the components already described above which are necessary in order co convey binders and/or additives out of the silo, for example by means of a feed screw or a pressure conveying device.
Alternately or preferably in addition to the described use of silo containers or intermediate binder containers, which serve as containers for concrete raw materials, in an advantageous development of the transportable concrete mixing plant according to the invention, provision can be made for at least one intermediate binder vessel for the intermediate storage of binder to be arranged in a stackable mixer container, a binder delivery means, preferably a binder feed screw, for delivering binder from at least one intermediate binder container into a binder compartment advantageously being arranged in the stackable mixer container. This ensures that the transportable concrete mixing plant according to the invention can continue to work even when the feed of binder from one or more silo containers or intermediate binder containers is temporarily interrupted, for example whilst they are being filled. In this case, the binder compartment in the stackable mixer container can be specifically supplied with binder from the intermediate binder vessel by the binder delivery means. It goes without saying that, depending on the relative arrangement of the binder compartment and the intermediate binder vessel, the binder delivery means can, for example, also be formed by a chute, a simple hose, a pressure conveying device or the like.
In order to be able to carry out the supplying of the mixer with binder and/or additives in the most flexible way, and in order in this way to be able to change flexibly between various binder supply states of the plant, provision is advantageously made for the transportable concrete mixing plant according to the invention to be designed to deliver binder and/or additives from a silo container and/or a transport vehicle into an intermediate binder vessel and/or an intermediate binder container, preferably having a feed-screw arrangement and/or a pressure conveying device. The feed-screw arrangement and/or the pressure conveying device, as described above, can be fitted in a stationary manner on or in one or more silo containers, in order to convey binder or additives from the silo into an intermediate vessel in a stackable mixer container or into an intermediate container which is erected on a stackable mixer container. However, a feed-screw arrangement or pressure conveying device of this type can also be provided separately from the silo containers when the plant is operating, in order to convey binders or additives directly from heavy goods vehicles which deliver the appropriate substances.
In a practical implementation of the transportable concrete mixing plant according to the invention, provision can be made for a mixer container, when the plant is operating, to be set up on its ends on at least one other container in each case in such a way that concrete can be let out through the openable hatches for removing concrete from the mixer container into a heavy goods vehicle or the like provided under the mixer container. AS in the case explained above of erection on a mixer frame, in the case of such an erection of the mixer container, the concrete prepared in the mixer can also be let out directly into the heavy goods vehicle provided. In addition, mixer containers having a number of mixers, which may be too heavy to be placed on a mixer frame, can be erected safely and without stability problems in the manner described with their ends on at least one other container in each case. It goes without saying that the at least two other containers on which a mixer container of this type is erected can be formed by virtually any other containers of the concrete mixing plant according to the invention, for example by control-station containers and/or water containers and/or containers for concrete additives.
The invention further relates to the use of a container, preferably a standard shipping container, especially in the transportable concrete mixing plant described above, as a binder silo. A binder silo of this type in the form of a container can be transported without difficulties over great distances, using marine freighters, goods trains, heavy goods vehicles and so on. Furthermore, the use of containers as binder silos offers the possibility of combining a number of containers, generally stacked on one another, to form larger silos.
In addition, the invention relates to a method of securing a binder or additive silo, preferably a container used as a binder silo, in a concrete mixing plant against falling over, in which method the binder silo is fastened by means of transverse struts to components of the concrete mixing plant. This type of fastening leads to greater stability than the conventional fastenings to the ground and thus reduces the risk of a largely emptied binder silo falling over in the event of severe wind or other vibration.
Furthermore, the invention relates to a conveying means, preferably a conveyor belt, having a conveying direction which can be changed over optionally and which can also be moved to and fro in the longitudinal direction between various operating positions. A conveying means of this type represents a quick-acting and space-saving device for distributing materials from a feed device to a number of holding devices, especially more than two holding devices arranged essentially beside one another.
Furthermore, the invention relates to a metering attachment for enlarging the effective catching cross section of a hopper of a metering unit, preferably of the metering-unit container in the above-described transportable concrete mixing plant, which is characterized by the fact that the metering attachment is formed by a stackable metering container which can be divided into two halves and whose halves, stacked beside each other on the metering unit, extend the inclined walls of the hopper upwards by means of fixed baffle plates in the interior of the halves and baffle plates which can be folded outwards. The enlargement effected hereby of the effective catching cross section of the hopper reduces the risk of the material to be put in xe2x80x9cfalling by the waysidexe2x80x9d, and thus permits the rapid filling of the hopper and simultaneous filling with the aid of a number of feed devices, for example in the form of wheeled loaders.